Magnetic resonance portal venography: use of fast-acquisition true FISP imaging in the detection of portal vein thrombosis

AIM: To determine the accuracy of true fast imaging with steady-state precession (true FISP) in the diagnosis of portal vein thrombosis in patients with cirrhosis and compare it to contrast-enhanced three-dimensional (3D) magnetic resonance (MR) angiography, the reference standard. MATERIALS AND METHODS: Twenty-four consecutive patients with suspected portal venous thrombosis underwent contrast-enhanced 3D MR angiography and true FISP imaging of the portal vein. All patients had undergone at least one other imaging study, either computed tomography, (CT) or ultrasound. Both sets of MR images were evaluated for patency of the portal venous system and for image quality. RESULTS: Portal vein thrombosis was diagnosed in six of the 24 patients. Four patients with portal vein thrombosis were accurately diagnosed on the true FISP sequence. This sequence also accurately diagnosed the patency of the portal vein in 17 patients. However, the results were inconclusive in three patients. The image quality of the true FISP sequence of the three inconclusive patients was graded as either poor or fair. Of these three patients, contrast-enhanced 3D MR angiography confirmed portal vein thrombosis in two patients and portal vein stenosis in one patient. True FISP imaging had a sensitivity of 67% and a specificity of 100% for the diagnosis of portal vein thrombosis. CONCLUSION: The results of the present study show that the true FISP sequence is useful in diagnosing portal vein thrombosis. It could be employed as an adjunct to contrast-enhanced MR angiography in the severely debilitated patient where respiratory motion may degrade the images or in patients where the use of intravenous contrast medium is not possible due to poor venous access.     

Lymph node metastasis: ultrasmall superparamagnetic iron oxide-enhanced MR imaging versus PET/CT in a rabbit model

PURPOSE: To prospectively compare the diagnostic accuracy of ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging and integrated positron emission tomography-computed tomography (PET/CT) for the depiction of lymph node metastasis in an animal model, with histologic findings as the reference standard. MATERIALS AND METHODS: This experiment was approved by the local animal care committee. VX2 carcinoma was implanted into the thighs of 11 rabbits 4 weeks before the imaging study. T2- and T2*-weighted MR examinations were performed 24 hours after USPIO administration, followed by integrated PET/CT. USPIO-enhanced MR imaging and PET/CT analysis for the evaluation of the presence of metastasis in iliac lymph nodes were performed independently by two radiologists and two nuclear medicine physicians, respectively, without histopathologic knowledge. Results were evaluated by using receiver operating characteristic (ROC) analysis, and sensitivities and specificities were compared by using a Z test. RESULTS: Metastases were histopathologically confirmed in 22 of 62 iliac lymph nodes. USPIO-enhanced MR imaging showed a significantly greater area under the ROC curve than did PET/CT (0.984 vs 0.852; P=.023). The respective sensitivity and specificity for the detection of lymph node metastasis were 91% (20 of 22) and 95% (38 of 40) for USPIO-enhanced MR imaging and 64% (14 of 22) and 98% (39 of 40) for PET/CT. In terms of sensitivity, a significant difference was found between USPIO-enhanced MR imaging and PET/CT, particularly for nodal metastasis of less than 5 mm (86% [six of seven] vs 0% [zero of seven]; P=.031), whereas the specificity of the two imaging modalities was similar (P=.226). CONCLUSION: USPIO-enhanced MR imaging results in higher diagnostic accuracy for depicting lymph node metastasis than does PET/CT.     

Hepatic flow parameters measured with MR imaging and Doppler US: correlations with degree of cirrhosis and portal hypertension

PURPOSE: To determine the correlations between hemodynamic parameters of hepatic flow measured with magnetic resonance (MR) imaging and Doppler ultrasonography (US) and the severity of cirrhosis and portal hypertension. MATERIALS AND METHODS: Forty-six patients referred for measurements of portal venous pressure (three with normal liver, 12 with chronic hepatitis, and 31 with cirrhosis [10 with Child-Pugh class A cirrhosis; 13 with class B cirrhosis; and eight with class C cirrhosis]) were included in the study. Apparent liver perfusion, apparent arterial and portal perfusion, portal fraction, distribution volume, and mean transit time were measured with dynamic contrast material-enhanced MR imaging. Portal velocity, portal flow, congestion index, right hepatic artery resistance index, and modified hepatic index were measured with Doppler US. Results in patients with cirrhosis and those without cirrhosis were compared with the Wilcoxon rank sum test. Correlations were assessed with Spearman rank correlation coefficients. RESULTS: With MR imaging, all flow parameters except distribution volume were significantly different between patients with and those without cirrhosis (P <.05). There was a significant correlation between all flow parameters measured with MR imaging and portal pressure (P <.02). Apparent arterial (P =.024) and portal (P <.001) perfusion, portal fraction (P <.001), and mean transit time (P =.004) were correlated with Child-Pugh class. Flow parameters measured with Doppler US did not differ significantly between patients with and those without cirrhosis. Only right hepatic arterial resistance (P <.007) and portal flow (P <.043) were weakly (r < 0.7) correlated with portal pressure. No Doppler US parameter was correlated with Child-Pugh class. CONCLUSION: Hepatic flow parameters measured with MR imaging correlate with the severity of cirrhosis and portal hypertension. Doppler US parameters are only weakly correlated with portal pressure.     

增强磁共振门静脉造影对门脉高压症的初步探讨

评价增强磁共振门脉造影对门脉高压症的诊断价值及探讨其在术前选择手术方式和术后评价疗效的可行性。材料与方法：对３０例门脉高压症患者和１０例正常人进行增强磁共振门脉造影。使用西门子１．５Ｔ超导型磁共振仪,体部序列线圈,采用三维屏气ＦＩＳＰ、短ＴＲ／ＴＥ序我。     

Timing bolus dynamic contrast‐enhanced (DCE) MRI assessment of hepatic perfusion: Initial experience

Purpose

To assess whether dynamic contrast‐enhanced (DCE) MRI timing bolus data from routine clinical examinations can be postprocessed to obtain hepatic perfusion parameters for diagnosing cirrhosis.

Materials and Methods

We retrospectively identified 57 patients (22 with cirrhosis and 35 without cirrhosis) who underwent abdominal MRI, which included a low‐dose (2 mL gadodiamide) timing bolus using a volumetric spoiled gradient echo T1‐weighted sequence through the abdomen. Using a dual‐input single‐compartment model, the following perfusion parameters were measured: arterial, portal, and total blood flow; arterial fraction; mean transit time; and distribution volume. Those parameters were compared between patients with and without cirrhosis using t‐tests. Receiver operating characteristic (ROC) curve analysis was used to identify the perfusion parameters that can best predict the presence of cirrhosis.

Results

The hepatic arterial fraction, arterial flow, and distribution volume in patients with cirrhosis (27.7 ± 8.3%, 44.8 ± 14.1 mL/minute/100 g, and 16.3 ± 4.5%, respectively) were significantly higher than those without cirrhosis (18.7 ± 4.4%, 28.5 ± 11.7 mL/minute/100 g, and 14.0 ± 4.2%, respectively; P < 0.05 for all). ROC analysis showed arterial fraction as the best predictor of cirrhosis, with sensitivity of 73% and specificity of 86%.

Conclusion

Timing bolus DCE MR images from routine examinations can be postprocessed to yield potentially useful hepatic perfusion parameters. J. Magn. Reson. Imaging 2009;29:1317–1322. © 2009 Wiley‐Liss, Inc.     

Primary biliary cirrhosis: MR imaging findings and description of MR imaging periportal halo sign

OBJECTIVE: This study reviews the prevalence of MR imaging abnormalities seen in 21 consecutive patients with primary biliary cirrhosis before transplantation and describes a new MR imaging sign in these patients: the MR imaging periportal halo sign. CONCLUSION: Abdominal adenopathy was present in 62% of the patient population, and none of the patients with adenopathy had a known malignancy. Findings associated with end-stage cirrhosis and portal hypertension were seen and included ascites (62%), splenomegaly (71%), portosystemic collaterals (57%), portal vein thrombosis (5%), and hepatocellular carcinoma (5%). The MR imaging periportal halo sign was seen in 43% of patients with primary biliary cirrhosis, but none of the patients in a sex- and age-matched cohort of 21 patients with cirrhosis not caused by primary biliary cirrhosis had the finding. Statistical analysis of these results produced a t score of 3.97 and a p value of less than 0.001, suggesting that this new MR imaging sign is highly specific for the diagnosis of primary biliary cirrhosis.     

Liver lesions: manganese-enhanced MR and dual-phase helical CT for preoperative detection and characterization comparison with receiver operating characteristic analysis

PURPOSE: The purpose of this study was to compare, by means of receiver operating characteristic (ROC) analysis, dual-phase helical computed tomography (CT) and manganese-enhanced magnetic resonance (MR) imaging in the detection and characterization of hepatic lesions in patients prior to surgery. MATERIALS AND METHODS: Twenty-five patients known to have or suspected of having hepatic lesions who were eligible for surgery underwent dual-phase (ie, arterial and portal phase) helical CT and phased-array MR imaging (ie, unenhanced fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging performed before and after administration of mangafodipir trisodium). All images were reviewed independently by three off-site blinded reviewers who separately reviewed the CT scans and MR images. The standard of reference was findings at surgery, intraoperative ultrasonography (US), and histopathologic examination. ROC curves were established to analyze the results for each reader and modality. RESULTS: Ninety-four lesions (77 malignant and 17 benign) were revealed at surgery, intraoperative US, and/or histopathologic examination. The overall rate of lesion detection for the three readers at CT was 81.9% +/- 7.8, 90.4% +/- 5.9, and 76.6% +/- 8.6. At MR imaging, the detection rates were 72.3% +/- 9.0, 71.3% +/- 9.1, and 69.1% +/- 9.3 (P =.001 for the difference between MR and CT). The average rate of false-positive diagnoses in patients was 14.1% at CT and 6.4% at MR imaging (P =.06 for the difference between MR and CT). The mean areas under the alternative-free-response ROC curves were 0.74 for MR and 0.72 for CT (P =.751, not significant). CONCLUSION: In detection and characterization of liver lesions, manganese-enhanced MR imaging and dual-phase helical CT were not statistically different.     

电子束CT血管造影在肝硬化门脉高压的诊断和临床应用

目的：分析肝硬化门脉高压电子束CT血管造影表现，探讨其临床应用价值。方法：收集24例肝硬化门脉高压患者，行3mm薄层连续容积扫描，使用MIP和SSD三维血管重建。结果：食道下端静脉曲张9例，胃底贲门静脉曲张13例，肝门静脉曲张6例，脾门处脾静脉扭曲扩张11例，2例脾肾静脉自发分流，3例附脐静脉开放，2例肝硬化合并肝癌。结论：电子束CT血管造影及血管三维重建在肝硬化门脉高压诊断中具有重要作用，对TIPSS手术的术前评估和术后随访有着积极的指导作用。     

Intraportal venous flow distribution: evaluation with single breath-hold ECG-triggered three-dimensional half-Fourier fast spin-echo MR imaging and a selective inversion-recovery tagging pulse.

OBJECTIVE: The purpose of this study was to evaluate the intraportal blood flow distribution from splenic and superior mesenteric veins with an unenhanced MR angiographic technique using single breath-hold ECG-triggered three-dimensional (3D) half-Fourier fast spin-echo sequence and selective inversion-recovery tagging pulse. SUBJECTS AND METHODS: Seventeen healthy volunteers were included in this prospective study. After obtaining regular single breath-hold ECG-triggered 3D half-Fourier fast spin-echo images without applying a tagging pulse, we placed the selective inversion-recovery tagging pulse on the superior mesenteric vein (TAG-A), the splenic vein (TAG-B), or on both (TAG-C) to study the inflow correlation of tagged or marked blood into the portal vein. MR images were evaluated subjectively by three reviewers. RESULTS: On MR images obtained using the TAG-A pulse to suppress the signal flow from the superior mesenteric vein into the portal vein, the most common pattern of signal loss was observed on the right half of the main portal vein (8/17 subjects). Conversely, on the MR images obtained using the TAG-B pulse, signal loss of the left half of the main portal vein was the most common pattern (11/17 subjects). Signal reduction from the splenic venous flow in the left portal vein was significantly greater than that from the superior mesenteric venous flow (p<0.05). CONCLUSION: The unenhanced MR angiographic technique using single breath-hold ECG-triggered 3D half-Fourier fast spin echo with selective inversion-recovery tagging pulse has the potential to assess the intraportal blood flow distribution from the splenic and superior mesenteric veins.     

门静脉高压患者舌下脉络相关改变的口腔内彩色多普勒超声研究

目的:探讨肝硬化患者门脉高压时舌下脉络(舌下神经伴行静脉)的口腔内超声图像特征。方法:对44例肝硬化门脉高压患者、50例健康者舌下神经伴行静脉,运用腔内探头进行二维彩色多普勒(CDFI)及脉冲多普勒(PW)的超声检查,测量其内径及最大血流速度,并对其结果加以对比。结果:门脉高压组较正常组舌下神经伴行静脉内径明显增宽,血流速度明显减低。结论:口腔内彩色多普勒超声可为肝硬化门脉高压时舌下脉络的观测提供定量指标。     

Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MR imaging--a meta-analysis

PURPOSE: To perform a meta-analysis to compare endoluminal ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging in rectal cancer staging. MATERIALS AND METHODS: Relevant articles published between 1985 and 2002 were included if more than 20 patients were studied, histopathologic findings were the reference standard, and data were presented for 2 x 2 tables; articles were excluded if data were reported elsewhere in more detail. Two reviewers independently extracted data on study characteristics and results. Bivariate random-effects approach was used to obtain summary estimates of sensitivity and specificity for invasion of muscularis propria, perirectal tissue, and adjacent organs and for lymph node involvement. Summary receiver operating characteristic (ROC) curves were fitted for perirectal tissue invasion and lymph node involvement. RESULTS: Ninety articles fulfilled all inclusion criteria. For muscularis propria invasion, US and MR imaging had similar sensitivities; specificity of US (86% [95% confidence interval [CI]: 80, 90]) was significantly higher than that of MR imaging (69% [95% CI: 52, 82]) (P =.02). For perirectal tissue invasion, sensitivity of US (90% [95% CI: 88, 92]) was significantly higher than that of CT (79% [95% CI: 74, 84]) (P <.001) and MR imaging (82% [95% CI: 74, 87]) (P =.003); specificities were comparable. For adjacent organ invasion and lymph node involvement, estimates for US, CT, and MR imaging were comparable. Summary ROC curve for US of perirectal tissue invasion showed better diagnostic accuracy than that of CT and MR imaging. Summary ROC curves for lymph node involvement showed no differences in accuracy. CONCLUSION: For local invasion, endoluminal US was most accurate and can be helpful in screening patients for available therapeutic strategies.     

MR venography of the inferior mesentery vein

OBJECTIVE: To evaluate on three-dimensional (3D) dynamic contrast-enhanced (DCE) MR venography (MRV), the visibility of the inferior mesenteric vein (IMV), its insertion pattern into the portal system, and the difference of IMV diameters between healthy subjects and patients with cirrhosis. MATERIALS AND METHODS: Two hundred and seventeen consecutive patients who had abdominal 3D DCE MRI was included in this study. The original image data of 3D DCE MRI was used to generate multiple planar volume reconstruction (MPVR) images, which were evaluated for visualization of the IMV and its pattern of insertion into the portal system. The diameter of IMV was measured and compared in 24 patients with cirrhosis (Cirrhosis Group) and in 30 patients without hepatic lesions or liver disease (Healthy Group). RESULTS: In the 217 patients, the frequencies of visualization of IMV, grade 1 order branches and grade 2 order branches were, respectively, 88%, 24% and 9%. The IMV inserted into the splenic vein (SV), the portal confluence and the superior mesenteric vein (SMV) in 45%, 18% and 37%, respectively. Among patients with cirrhosis, 12.5% had IMV diameter larger than 5.1mm, although there was no significant difference between cirrhosis and healthy groups (P>0.05). However, the diameters of the main portal vein (MPV), SV and SMV were significantly larger in the Cirrhosis Group (P<0.05). CONCLUSION: The IMV and its branches can be depicted well by 3D DCE MRV. The most common insertion of the IMV is into the splenic vein. A minority of patients with cirrhosis had dilatation of the IMV.     

Cirrhosis: value of caudate to right lobe ratio in diagnosis with US

To verify the value of ultrasound (US) in the diagnosis of cirrhosis, the ratio of transverse caudate lobe width to right lobe width (C/RL) was determined with US in 25 healthy subjects and 156 consecutive patients with either histologically proved acute viral, chronic persistent, or chronic active hepatitis or cirrhosis. The C/RL ratio had a sensitivity of 43%, a specificity of 100%, and an accuracy of 79% in cirrhosis. The sensitivity was very low in alcoholic cirrhosis, low in cryptogenic cirrhosis, and high in hepatitis B virus related cirrhosis. In spite of its fairly low overall sensitivity, the C/RL ratio is a useful measurement in assessing chronic liver disease because of its high specificity in cirrhosis.     

Detection of hepatic metastases: comparison of contrast-enhanced CT, unenhanced MR imaging, and iron oxide-enhanced MR imaging

Diagnostic accuracy of contrast-enhanced CT, unenhanced MR imaging, and MR images enhanced with superparamagnetic iron oxide was evaluated in 10 patients with histologically proved hepatic metastases. First, diagnostic performance of the imaging technique with respect to the ability of radiologists to recognize the presence or absence of a metastasis was measured by using receiver-operating-characteristic (ROC) analysis of single images. Second, the total number of lesions (N = 108) detected by "complete" CT and MR examinations was counted. Finally, lesion-liver contrast-to-noise ratios (CNR) were measured in all MR sequences. The area under the ROC curve was .67 +/- .03 for contrast-enhanced CT, .81 +/- .07 for the unenhanced SE 260/14 sequence, and .92 +/- .01 for the iron oxide-enhanced SE 1500/40 sequence. The enhanced SE 1500/40 sequence yielded significantly (p less than .005) greater accuracy than did contrast-enhanced CT. The same sequence detected significantly (p less than .05) more lesions than all other imaging techniques (19% more than the best unenhanced MR sequence and 36% more than contrast-enhanced CT). The enhanced SE 1500/40 sequence also yielded the highest CNR value (19.5 +/- 10.2) of all MR sequences. These results indicate that iron oxide-enhanced MR imaging is a superior imaging technique for the detection of hepatic lesions.     

Vascular complications after living related liver transplantation: evaluation with gadolinium-enhanced three-dimensional MR angiography

OBJECTIVE: The purpose of this study was to evaluate the efficacy of gadolinium-enhanced three-dimensional (3D) MR angiography for detection of vascular complications in patients who have undergone living related liver transplantation. MATERIALS AND METHODS: Seventy-six patients who underwent living related liver transplantation were evaluated with gadolinium-enhanced 3D MR angiography. All MR angiograms were assessed for patency of the hepatic artery and the portal vein using a four-point scale (grades I-IV). The results were correlated with conventional angiography (n = 23) and clinical follow-up with Doppler sonography (n = 53) for more than 6 months. RESULTS: Seventy-three of 76 MR angiography procedures were technically adequate. When grades III (focal narrowing [> 50%] at the anastomotic site) and IV (abrupt cutoff at the anastomotic site with nonvisualization of the right [or left] hepatic artery distal to the anastomosis) were regarded as the diagnostic criteria for hepatic artery stenosis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR angiography were 100%, 74%, 29%, 100%, and 77%, respectively. In the portal vein, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR angiography were 100%, 84%, 35%, 100%, and 85%, respectively, when grades III (narrowing [> 50%] without poststenotic dilatation) and IV (narrowing [> 50%] with poststenotic dilatation) were defined as criteria for portal vein stenosis. CONCLUSION: MR angiography was sensitive but not specific in the detection of significant vascular stenosis after living related liver transplantation. However, normal MR angiography findings reliably exclude the possibility of significant stenosis.     

CT signs of hepatofugal portal venous flow in patients with cirrhosis

OBJECTIVE: We investigated whether CT signs can be used to predict hepatofugal flow in the main portal vein in patients with cirrhosis. MATERIALS AND METHODS: We retrospectively identified 36 patients with cirrhosis, 18 with hepatopetal and 18 with hepatofugal flow in the main portal vein, who underwent contemporaneous abdominal sonography and CT. Two independent observers evaluated the following features on the randomized CT studies: diameter of the portal, splenic, and superior mesenteric veins; spleen size; and the presence of ascites, varices, or arterial phase portal venous enhancement. These data were correlated with the flow direction seen on sonography. RESULTS: A small main portal vein was the only sign significantly (p 相似文献   

Detection of thrombosis in the portal venous system: comparison of contrast-enhanced MR angiography with intraarterial digital subtraction angiography

PURPOSE: To determine whether intraarterial digital subtraction angiography (DSA) can be replaced by contrast material-enhanced magnetic resonance (MR) angiography in the assessment of patency or thrombosis of the portal venous system in patients with portal hypertension. MATERIALS AND METHODS: Thirty-six patients with portal hypertension underwent contrast-enhanced MR angiography and intraarterial DSA for assessment of the portal venous system. The images were evaluated for vessel patency or thrombosis of the portal, splenic, or superior mesenteric vein. RESULTS: Of the 101 vessels evaluated, 42 were thrombosed. Overall sensitivity, specificity, and accuracy for the detection of thrombosis were 100%, 98%, and 99%, respectively, for MR angiography and 91%, 100%, and 96%, respectively, for DSA; differences between the imaging methods were not statistically significant. Only in four patients with six vessels (6%) were there discordant findings between MR angiography and DSA. CONCLUSION: Noninvasive contrast-enhanced MR angiography has the potential to replace intraarterial DSA as the standard method to assess the whole portal venous system.     

Assessment of portal vein patency: comparison of arterial portography and ultrasound scanning

The accuracy of ultrasound assessment of portal vein patency has been defined by comparing it with the results of arterial portography in 115 cases. The accuracy of arterial portography was confirmed in 21 cases where orthotopic liver transplantation was performed and used as a 'bench-mark' against which to assess the ultrasound findings. Ultrasound correctly assessed portal vein patency in 87.5% of patients. It was more accurate in assessing patency (90%) than occlusion (68%). Ultrasound correctly assessed portal vein patency in 90% of cases of cirrhosis and hepatic malignancy. Difficulties occurred in children with biliary atresia particularly following the Kasai operation (37.5% accuracy). In the absence of previous surgery to the portal vein or biliary system, ultrasound is comparable to arterial portography and can be used as the sole means of assessment.     

Liver transplantation: MR angiography with surgical validation

Thirty patients (mean age, 45 years) were evaluated with magnetic resonance (MR) angiography before liver transplantation to assess the accuracy of MR angiography. A series of breath-hold, two-dimensional images were acquired and subsequently processed to form three-dimensional projection angiograms. Graphic information on blood flow in the portal vein was acquired by using presaturation bolus tracking. Correlative duplex ultrasound (US) was performed in 28 patients, and surgical or autopsy correlation was available in all cases. MR angiography demonstrated patency of the portal vein in 26 (96%) of 27 patients, made possible the diagnosis of portal venous occlusion in three of three patients, depicted reversed portal flow in one patient, and provided clear delineation of the extent of varices and specific portosystemic collateral vessels. When duplex US was successful, there was full agreement with MR angiographic results in assessing portal vein patency and flow direction. All of the MR findings were corroborated at surgical exploration or autopsy. The authors conclude that MR angiography is very accurate in the portal system and is valuable in preoperative assessment for liver transplantation.     

SCTAP评价肝硬化及门静脉高压的临床价值

目的 :评价螺旋CT经动脉门静脉造影 (SCTAP)对肝硬化、门静脉高压判断的临床价值。方法 :根据临床综合诊断标准 ,比较 2 6例采用常规CT、SCTAP轴位及MIP法三维重建判断肝硬化、门静脉高压的结果。结果 :SCTAP对门静脉远侧分支的显示明显优于常规CT(P <0 .0 1)。SCTAP轴位能较好显示门静脉细小分支的异常改变 ,对肝硬化判断的敏感性为 93.3%。SCTAP MIP能直观地显示门静脉的全貌及侧支循环通路 ,对门静脉高压的判断的特异性为 94 .1%。常规CT能较全面反映门静脉高压的肝外征象 (脾大、腹水 )。结论 :SCTAP与常规CT、临床及实验室检查结合 ,有助于肝硬化、门静脉高压的准确判断。